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PATTERNS OF NITRATE LOSSES FROM FORESTED BASINS IN THE OREGON COAST RANGE
Citation:
Church, M R., J E. Compton, AND S T. Larned. PATTERNS OF NITRATE LOSSES FROM FORESTED BASINS IN THE OREGON COAST RANGE. Presented at 2001 Gordon Research Conference on Hydrological, Geochemical, and Biological Processes of Forested Catchments, Andover, NH, July 22-27, 2001.
Description:
Numerous factors may control losses of dissolved nutrients from forested basins in the Oregon Coast Range. Potentially important factors include forest composition, stand age, forest management, grazing, agriculture, sewage inputs and bedrock types, as well as others perhaps not previously appreciated. With understanding of processes and controls may come the ability to model, predict and extrapolate current and future conditions across the Coast Range. To better understand the controls on nutrient losses from coastal watersheds, we sampled over 45 sites on the main stem and tributaries of the Salmon River in the Oregon Coast Range monthly since January 2000. The Salmon River basin is characterized by old soils with large stores of soil nitrogen, presumably resulting from long-term inputs by nitrogen-fixing red alder. We measured all major chemical constituents, with a focus on organic and inorganic nitrogen, and also determined instantaneous stream flow at approximately two-thirds of our sites.
Nitrate concentrations in these streams ranged from zero to nearly 3 ppm nitrate-N. Our data to date show a surprising correlation between losses of nitrate from the basin and losses of chloride, indicating that the inputs of chloride from sea spray play a role in nitrogen losses from these watersheds. In addition, at equal chloride concentration, areal coverage of alder within sub-basins is positively related to stream nitrate concentration.